Vibration isolation of power head



United States Patent 2,909,031 VIBRATION ISOLATION OF POWER HEAD Elmer Carl Kiekhaefer, Cedar-burg, Wis.

Application July 12, 1957, Serial N0 611,443 4 Claims. (Cl. 60- 31) This invention relates to outboard motors and in particular to means for mounting the powerhead and its component parts within the cowl so as to isolate the powerhead vibrations from the rest of the unit. 1 The vibrations set up by an outboard motor are not only objectionable to the occupants of the boat, but are also detrimental to the life of the various parts of the units and boat. The problem has become particularly aggravated in recent years with the advent of larger and more powerful engines.

Attempts have been made to isolate the vibrations of the motor from the boat through the use of elastic mountings between the driveshaft housing and the stern bracket. These resilient mountings have proved quite successful in isolating the vibrations from the boat itself.

It has been found highly desirable, however, to isolate the powerhead vibrations at a location closer to their source of origin. In attempting to do this by mounting the powerhead itself on resilient mounts, numerous other problems have arisen.

In accordance with this invention, a suspension system is provided for an outboard powerhead and its component parts which substantially prevents any powerhead vibration from reaching the driveshaft housing. The im vention contemplates sealing the engine exhaust pipe in the driveshaft housing by means of a flexible diaphragm. Water cooling is provided for the exhaust pipe at the point where the latter is in sealing engagement with the diaphragm. The cooling water may be sprayed against the diaphragm as well as against the driveshaft housing for cooling purposes.

. Other objects and advantages of the invention will be apparent from the accompanying drawing which illustrates the best mode presently contemplated by the inventor for carrying out-the invention.

7 The drawing is a fragmentary, elevational side view of an outboard motor embodying this invention, certain parts being broken away and others in section for the sake of clarity.

Referring more particularly to the drawings, the swivel bracket 10 is secured to the stern 11 of a boat by tightening the hand screws 13 of the clamp bracket 14.

The drive shaft housing 15 is pivotally secured to the swivel bracket 10 by means of the swivel pin assembly 10a. A lower pair of resilient mounts 16 (only one shown), and the pair of upper mounts 17 (only one shown), are secured to the drive shaft housing. Mounting bolts 25 extend through the assembly 10a and mounts 16, 17.

The drive shaft 18 extends downwardly through the hollow housing 15 for connection through a bevel gear unit (not shown) to the propeller 19. The housing 15 also defines an exhaust port 20 which is usually submerged in operation.

The drive shaft housing has flange portions 21, 22 extending around its upper end and upon which the engine 7 cowling 23 is secured by bolt means 24.

time

2 The powerhead 26 is of 'the water cooled internal-com bustion type and is mounted on a plurality of heavy rubber-like blocks or mounts 28 which are seated on the cowling 23. Some of the bolt means 24 extend through the mounts 28 and through registering apertures in the powerhead. Thus the powerhead proper, which is the source of major vibratory forces in an outboard motor, is elastically isolated from the driveshaft housing, and is free to vibrate within the cowling 23. Only an insignificant amount of vibration is transmitted to the cowling and then to the driveshaft housing. This small amount of transmitted engine vibration and whatever vibration originates from the propeller 19 are then isolated from the boat by means of elastic mounts 16, 17.

The powerhead exhausts via port 29 into exhaust stack 30 and then to the hollow drive shaft housing which in turn transmits the exhaust to the atmosphere or below the waterline via the port 20 in the housing.

Means have been provided for sealing the exhaust stack 30-into the driveshaft housing and at the same time insuring that no vibrations are transmitted from the exhaust stack to other parts of the motor. This means, comprises a flexible diaphragm 32 which has a molded bead portion'31 abutting against an annular ridge 31a on the stack. Thus the diaphragm seals the powerhead chamber from the driveshaft chamber so as to prevent leakage of water or fumes therebetween.

The diaphragm 32 also seals and vibrationally isolates the crankcase neck 33 which projects downwardly into the housing 15. The crankcase neck serves as a driveshaftsupport at the upper end of the latter. The driveshaft18 extends through the neck 33 from its splined connection to the crankshaft 34. A crankshaft seal 35 seals between the crankshaft and the crankcase neck 33. The lower end of the circular neck 33 has a lip 36 over which the aperture 37 in the diaphragm is slipped. The aperture 37 is defined by a bead portion 38 of the diaphragm which is molded integrally therein. Thus the neck is simply slipped into the aperture and the bead portion sealingly engages the neck against water or exhaust.

The outer edge of diaphragm 32 also has a molded bead portion 39 which is seated in a groove 40 in the upper edge of housing 15. The cowling 23 holds the bead portion 39 captive in the groove 40.

An, elastic coupling 41 is inserted in the driveshaft 18 so as to prevent any vibrations of the engine from being transmitted through the driveshaft to the driveshaft housing.

The diaphragm 32 thus seals the powerhead chamber from the driveshaft chamber so as to exclude water and exhaust from the former. The engine parts, such as the crankcase neck and exhaust stack, are not only effectively sealed into the driveshaft housing, but they are also vibrationally isolated therefrom, as is the driveshaft itself.

The exhaust stack 30 conducts both the engine exhaust and the engine cooling Water from the engine and into the driveshaft housing where it is ultimately discharged through the port 20. The stack 30 is of double wall construction and the cooling water is used to cool the stack at the point where the latter passes through the flexible diaphragm. The stack is secured to the engine by bolt means 42 and extends generally downwardly therefrom. The inner passage 44 conducts exhaust and discharges through its end 45 into the driveshaft housing. This exhaust is hot and the surrounding chamber 46 formed by the double wall construction serves to conduct the cooling Water from inlet 47 and out the main water discharge opening 48. Thus Water cools the exhaust stack and ibutes to increased diaphragm life. 7

Under certain conditions, additional cooling may be necessary for the diaphragm. This is accomplished by restricting the water discharge from the stack, by means of the relatively small opening, 48, thus causing some water pressure to be maintained within the water jacket. Diaphragm cooling jets 49 are formed in the outer wall of the stack and are directed to discharge water on, the diaphragm.

As a result the water spray helps to cool the entire diaphragm as well as the entire drive shaft housing.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. In an outboard motor unit including a cowling defining a powerhead chamber, an engine mounted in said chamber, elastic mounts disposed between the engine and cowling and permitting vibratory movement of the engine relative to the cowling and serving to isolate the majority of the engine vibrations from said cowling, a driveshaft housing defining a driveshaft chamber and secured to said cowling at the lower side of the latter, and exhaust stack extending downwardly from said engine into the driveshaft chamber and vibrating with said engine and adapted to receive the exhaust gases from the engine for discharge into said driveshafit chamber, and a flexible sealing member secured within said unit and separating said powerhead and driveshaft chambers to prevent ingress of exhaust gases to the powerhead chamber from the driveshaft chamber, said member being in sealing engagement with the exhaust stack and adapted to flex to accommodate the engine vibrations imparted to the stack.

2. In an outboard motor having a cowling defining a powerhead chamber, an engine mounted in said chamber, resilient mounting blocks disposed between the engine and cowling and permitting vibratory movement of the engine relative to the cowling and serving to isolate the majority of the engine vibrations from said cowling, a driveshaft housing defining a driveshaft chamber and secured to said cowling at the lower side-of the latter, a bearing support for the driveshaft extending downwardly from said engine into the driveshaft chamber, an exhaust stack also extending downwardly from said engine into the driveshaft chamber and vibrating with said engine and adapted to receive the exhaust gases from the engine for discharge into said driveshaft chamber, and a flexible sealing member secured between said driveshaft housing and said cowling for sealingly separating said powerhead chamber from the driveshaft chamber to prevent ingress of exhaust gases to the powerhead chamber from the driveshaft chamber,

said member being in sealing engagement with the bearing support and exhaust stack respectively and adapted to flex to accommodate the engine vibrations imparted to the bearing support and exhaust stack.

3. In an outboard motor unit including a cowling defining a powerhead chamber, an engine mounted in said chamber, elastic mounts disposed between the engine and cowling and permitting vibratory movement of the engine relative to the cowling and serving to isolate the majority of the engine vibrations from said cowling, a driveshaft housing defining a driveshaft chamber and secured to said cowling at the lower shide of the latter, an exhaust stack extending downwardly from said engine into the driveshaft chamber and vibrating with said engine, said exhaust stack comprising a central exhaust passage adapted to re ceive the exhaust gases from the engine, for discharge into said driveshaft chamber and an outer casing defining a cooling water chainber surrounding said passage, and a flexible sealing member secured within said unit and separating said powerhead and driveshaft, chambers to prevent ingress of exhaust gases to the powerhead chamber from the driveshaft chamber, said member being in sealing engagement with the outer casing of the exhaust stack and adapted to flex to accommodate the engine vibrations imparted to the stack.

' of the engine vibrations from said cowling, a driveshait housing defining a driveshaft chamber and secured to said cowling at the lower side of the latter, an exhaust; stack extending downwardly from said engine into the driveshaft chamber and vibrating with said engine, said exhaust stack comprising a central exhaust passage adapted to receive the exhaust gases from the engine for discharge into said driveshaft chamber and an outer C 8: ing defining a cooling water chamber surrounding said passage, said cooling water chamber receiving water under pressure for discharge through a downwardly directed discharge opening and having a plurality of upwardly di-. rected jet openings, and a diaphragm secured within said unit and separating said powerhead and driveshaft chambers to prevent ingress of exhaust gasesto the powerhead chamber from the driveshafit chamber, said diaphragm being in sealing engagement with the outer casing of the exhaust stack and adapted to flex to accommodate the engine vibrations imparted to the stack and subject to heating by the engine and the exhaust gases, said upwardly directedjet openings being adapted to spray the cooling water under pressure against the diaphragm to provide for cooling of the diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS 1,131,862 Perkins Mar. 16, 1915 2,024,193 Watkins Dec. 17, 1 935 2,206,258 Laguzzi July 2, 1940 2,585,774 Heidner et al Feb.{12,,i952 2,757,650 Holley Aug. 7, 1956 2,772,649 Gensheirner et al Dec. 4, 1956 

